Resistencia y capacidad para remover mercurio, de bacterias aisladas desde los suelos de las zonas mineras de Portovelo en Ecuador

Abstract

In this study, two strains of Gram negative bacteria were isolated from the soils of three mining areas of the Portovelo canton with the objective of determining their resistance to different concentrations of mercury (Hg) and evaluating their ability to remove this metal. Three soil samples were collected at random, in places where the use of Hg was detected in the separation of gold. The resistance capacity of the bacteria to Hg was evaluated in vitro, for this, the bacteria were extracted from the soil by inoculating 1 g of soil in solid culture media; the bacteria that grew and developed in these media were reseeded in media containing concentrations of 0; fifty; and 100 ppm of mercury chloride (HgCl2). Two strains of bacteria named BA and BN, showed resistance to different concentrations of HgCl2, these two strains were identified as a Gram Negative bacillus and a Great Negative coco, respectively. To evaluate the ability to remove Hg, the two bacterial strains were inoculated for 5 days in liquid medium with concentrations of 50 and 100 ppm of HgCl2, after the inoculation time had elapsed, the concentration of Hg in the media was less than 3 ppm, which means removal percentages greater than 96% by the two strains. In order to verify that this reduction in Hg concentration was given by the action of bacteria, the initial and final concentration of Hg in media that did not contain bacteria was also measured, after 5 days, the concentration in those media it did not change significantly, which suggests that the removal of Hg was caused by microbial action in the media that did contain bacteria. The results of this research contribute directly to the design of bioremediation strategies for soils contaminated by mining activities in the Portovelo areas.